Add support for encrypted WebM files as defined in the RFC.

media/base/decrypt_config.cc

Index: media/base/decrypt_config.cc
diff --git a/media/base/decrypt_config.cc b/media/base/decrypt_config.cc
index 9ae5f195e5d4cfab2be9a45108b23d329d2732e4..ea7cf3ee28f6e5de72761c4a4c4ad94ae89aa645 100644
--- a/media/base/decrypt_config.cc
+++ b/media/base/decrypt_config.cc
@@ -8,11 +8,26 @@
 
 namespace media {
 
-DecryptConfig::DecryptConfig(const uint8* key_id, int key_id_size)
-    : key_id_size_(key_id_size) {
+DecryptConfig::DecryptConfig(const uint8* key_id, int key_id_size,
+                             const uint8* iv, int iv_size,
+                             const uint8* checksum, int checksum_size,
+                             int encrypted_frame_offset)
+    :  key_id_size_(key_id_size),
+       iv_size_(iv_size),
+       checksum_size_(checksum_size),
+       encrypted_frame_offset_(encrypted_frame_offset) {
   CHECK_GT(key_id_size, 0);
+  CHECK_EQ(iv_size, 16);
+  CHECK_GE(checksum_size, 0);
+  CHECK_GE(encrypted_frame_offset, 0);
   key_id_.reset(new uint8[key_id_size]);
   memcpy(key_id_.get(), key_id, key_id_size);
+  iv_.reset(new uint8[iv_size]);
+  memcpy(iv_.get(), iv, iv_size);
+  if (checksum_size > 0) {
+    checksum_.reset(new uint8[checksum_size]);
+    memcpy(checksum_.get(), checksum, checksum_size);
+  }
 }
 
 DecryptConfig::~DecryptConfig() {}